Physical mapping of Nicotiana tabacum chloroplast DNA

Summary Nicotiana tabacum chloroplast DNA was digested with several restriction endonucleases chosen for their potential usefulness in distinguishing between species of the genus, Nicotiana. The resulting fragments were ordered into a circular configuration of about 160 kilobase pairs, equalling about 100x10⁶ daltons. The physical map features an inverted, repeated unit of about 24 kilobase pairs separated by a unique sequence region with a mean size of 13 kilobase pairs on the short side. The cistrons coding for chloroplast ribosomal RNA are contained within the inverted repeat and have the arrangement: 16S, spacer, 23S, 4.5S/5S. Restriction endonuclease maps obtained with the enzymes PvuII, XhoI, and BglI are presented.